Lifting ring

ABSTRACT

A lifting ring having a lifting shackle and a yoke for coupling to the head of an anchoring device, the yoke being pivotally mounted to the bottom portion of the lifting shackle which is formed with two toroidal surfaces. The lifting shackle is formed with an eye which opens out onto the toroidal surfaces, the eye having two coupling faces and two inclined faces forming abutments that limit the relative motion possible between the yoke and the shackle.

The present invention relates to a lifting ring designed for lifting,transporting, or turning over heavy loads, such as prefabricatedbuilding elements, in particular after said elements have been molded,where said elements are particularly, but not exclusively, thin panels.

BACKGROUND OF THE INVENTION

Such rings are known and used on a wide scale. Their purpose is toenable a mechanical link to be established between an anchoring deviceincorporated in the concrete and a hook of a hoist such as crane.

More particularly, the present invention relates to a ring designed toco-operate with an anchoring device having an eye or a tear-out coneassociated with a cylindrical head, even though the ring may also beimplemented with other anchoring pieces.

When the concrete is being cast, the anchoring piece projects into avoid that is hemispherical or partially hemispherical so as to beaccessible after unmolding or removal of shuttering.

Such a ring is described in FR-A-1 568 605 and in FR-A-2 302 398(HAEUSSLER). It comprises a coupling piece or yoke for coupling with thehead of the anchoring device and a ring proper or shackle which providesthe connection between the coupling piece and the hook of the hoist.

The yoke includes a groove or slot in the form of a circular sector inwhich the head of the anchoring device is received. In certain knownlifting rings, the spherical coupling piece is hinged to the shackle insuch a manner as to be capable of pivoting between a position in whichthe head can be engaged and disengaged in the groove, and a transport orhandling position in which the head of the anchoring device is inabutment against the bottom of the groove.

The prefabricated element can thus be transported in complete safety solong as the rated load of the anchor piece corresponds to the weight ofthe element. After transport, the groove can be moved relative to thehead of the anchoring device until the disengagement position isreached.

The top portion of the yoke includes a hinge eye or hole extendingorthogonally to the plane of the groove and located eccentricallyrelative to the center of the hemispherical portion. The hook-receivingshackle is itself engaged in the hole by a circular section arc or rodthat enables the parts to be hinged relative to each other. In order tofacilitate relative rotation between the yoke and the head of theanchoring device, it is also known to provide said part with a handlingtab or arm. The tab may be remotely controlled by means of a cable.

It is necessary to prevent the shackle or coupling part spoiling thesurface of the concrete which is still somewhat fresh. That is to avoidsubsequent expensive finishing on-site.

OBJECTS AND SUMMARY OF THE INVENTION

An object of the present invention is to propose a lifting ring makingit possible to work in complete safety, even with thin panels, whilelimiting the movement of the yoke relative to the shackle. To this end,the body of the yoke is hemispherical and laterally truncated so as tobe capable of working with heads of anchoring devices included in narrowspaces as is made necessary by the thinness of certain prefabricatedpanels.

Proposals have already been made in FR-A-2 479 166 to limit suchmovement by acting while the yoke is in the locked position on the headof the anchoring device to bring the above-mentioned handling arm intoabutment against the transverse portion that is used for this purpose inthe ring of the shackle.

In the past, since the shape of the yoke has been substantiallyhemispherical or substantially a truncated hemisphere, the manufacturerhas ensured that the hinge hole of the shackle runs into connectionradii that leave a large amount of movement available, over more than180°, with abutment being formed as mentioned above.

The idea on which the invention is based consists in using the couplingwalls of the hinge hole as abutments for limiting relative motionbetween the yoke and the shackle.

According to the invention, the lifting ring for prefabricated buildingelements provided with anchoring pieces having cylindrical heads,comprises both a yoke or coupling piece for coupling with the head ofthe anchoring device and that includes a downwardly open semicircularT-groove of dimensions corresponding to those of the head and of theshank of the anchoring device, and a hoisting shackle on which saidcoupling piece is pivotally mounted by means of an eye, and wherein theeye of the coupling piece is circular in section and opens out into thetruncated faces of the yoke via toroidal rings whose bottom portions aredefined by two toroidal surfaces coupling with two plane faces that areinclined relative to the horizontal when the coupling piece surroundsthe head of the anchoring device.

Thus, the motion or pivoting of the coupling piece relative to theshackle is automatically limited by contact between the shackle and theplane faces that form abutments for the arc of the shackle in twoextreme positions.

According to another characteristic of the invention, the toroidal hingering is asymmetrical. That is to say it is thus possible to provide thedesired displacement which need not be the same on opposite sides of theaxis of the hole, by having different angles a₁ and a₂ for the inclinedplane faces.

BRIEF DESCRIPTION OF THE DRAWINGS

Other characteristics and advantages of the invention appear from thefollowing description of particular embodiments given purely asnon-limiting examples, and with reference to the accompanying drawings,in which:

FIG. 1 is a side view of the yoke;

FIG. 2 is a plan view of the yoke;

FIG. 3 is a vertical half-section view of the yoke on line III--III ofFIG. 1;

FIG. 4 is a view of the ring in its vertical traction position in linewith the axis of the anchoring device;

FIG. 5 is a view of the ring in its position for disengagement from orinsertion on an anchoring device;

FIG. 6 is a view of the ring in position for lifting a panel; and

FIG. 7 is a front view of a shackle in which the yoke is mounted.

MORE DETAILED DESCRIPTION

As mentioned above, the lifting ring shown in FIGS. 4 to 6 comprises acoupling piece or yoke 1 that is pivotally mounted on a shackle 2 thatserves to engage a hook (not shown) itself generally connected to theslings of a hoist. As can be seen in FIGS. 1 to 3, the yoke is generallyspherical in shape having two truncated faces 1a and comprising a bottomportion 3 and a top portion 4. The top portion 4 includes a hole or eye5 of diameter that is slightly greater than the diameter of the bottomarc or rod 21 of the shackle that passes through the eye. The eye 5 iscircular, eccentric, and opens out into the faces of the yoke 1 viarespective toroidal surfaces 8 (on either side of the hole 5). Thebottom portion of the displacement cavity for the shackle is constitutedby two toroidal coupling faces 6 and 6a with inclined faces 7 and 7athat are substantially plane and that converge on a zone 10. Theseportions are inclined relative to the horizontal axis H of the eye 5 andthey co-operate therewith to form respective angles a₁ and a₂ that serveto limit motion of the shackle by the construction of the yoke. Theangle a₁ is always less than 90° and may have a value of 10°, forexample. The angle a₂ may be equal to the angle a₁. However it iscapable of having a value that is greater than 90°, since motion of theshackle is not a problem on the outside. The 180° complement of theangles a₁ and a₂ is preferably greater than 90° in order to prevent theyoke accidentally detaching itself from the head of the anchoring deviceduring pivoting of the shackle.

The top portion 4 of the yoke 2 preferably has a spur 9 on which it ispossible to fix, in conventional manner, a remote-control cable byfixing a tube that is terminated by a ring on the spur, thereby enablingthe yoke 1 to be pivoted on the arc 21 of the shackle 2 once the panelhas been put into place by the hoist. Use of the spur is restricted tothe possibility of remote unhooking.

The cylindrical groove 11 can be seen in FIG. 3. The groove 11 is aT-section cylindrical groove that is open to the outside via an opening13. The bottom portion 12 of the groove 11 is open and extends over atleast one-fourth of a circle inside the hemispherical portion 3.

While the ring is in use (FIG. 4), the ring being shown in its liftingposition, the spur 9 is located above the center of the sphere, therebypreventing any contact between the spur and the concrete. The head ofthe anchoring device A is at the bottom of the groove 11. Handling canbe performed normally.

FIG. 5 shows the position of the yoke on the anchoring device A whilethe yoke is in its engagement or disengagement position (which positionsare the same). It can be seen that in this position the surface 7 isinclined at an angle a₁ relative to the vertical and acts as an abutmentfor the shackle 2, the yoke being incapable of rotating in the clockwisedirection, and being capable of rotating anticlockwise only so as toengage itself on the head of the anchor piece 1 which it receives in itsgroove 11. After the yoke 1 has been pivoted through 90° inside thespace (no reference), then the parts take up the configuration shown inFIG. 4.

In the two examples described above, the object of the exercise has beento lift a panel in which the anchoring device(s) is/are vertical. FIG. 6shows an example of how lifting can be performed with the anchoringdevice A being in a horizontal position. The yoke 1 is engaged on thehead of the anchoring device as before. Because of the abutments 6 and6a, the shackle cannot rotate beyond the vertical position. Whentransporting the element by means of slings, the shackle is commonlyinclined relative to the vertical and does not run any risk of damagingthe surface of the concrete, which is the looked-for result.

FIG. 7 shows a shackle 2 suitable for use with the yoke 1 as describedabove. The shackle comprises an arc 21 and another arc 23 that areassembled together by welding. Where the arcs 21 and 23 are joinedtogether, the arc 23 is preferably narrowed at 22 so as to avoid thehook bearing directly against the yoke 1.

We claim:
 1. A lifting ring for prefabricated building elements,provided with an anchoring piece having a cylindrical head and a shankabout an axis of symmetry, the lifting ring comprising both a couplingpiece or yoke for coupling with the head of the anchoring piece, thecoupling piece being generally spherical in shape having two paralleltruncated faces and including a downwardly open circular groove ofdimensions corresponding to those of the anchoring piece head and shank,and a lifting shackle on which said coupling piece is pivotally mountedby means of an eye that is eccentric relative to the center of the yokeand that extends in a direction that is orthogonal to the plane of thecircular groove, whereinthe eye of the coupling piece is circular insection and opens out into the truncated faces of the yoke viarespective toroidal surfaces whose bottom portions are defined by twotoroidal coupling faces coupling with two inclined faces that areinclined about the direction perpendicular to the axis of symmetry ofthe anchoring device when the coupling piece surrounds the head of theanchoring device.
 2. A lifting ring according to claim 1, wherein theinclined faces form angles a1 and a2 relative to said perpendiculardirection, the angles a1 and a2 being less than 90° such that theinclined faces form between them an angle which is less than 180° andgreater than 90°.
 3. A lifting ring according to claim 2, wherein theangles a1 and a2 are equal.
 4. A lifting ring according to claim 2,wherein the toroidal surfaces, coupling faces and inclined faces formclear internal abutments for the arc of the shackle, the angles a1 anda2 thereof defining the movement available to the shackle relative tothe coupling piece.
 5. A lifting ring according to claim 2, wherein the180° complement of the sum of the angles a₁ plus a₂ is greater than 90°.6. A lifting ring according to claim 1, wherein the eye has an axis ofsymmetry and the yoke is provided with a spur for remote identificationand control that is substantially level with the axis of the eye.